There have heretofore been proposed in the art a number of schemes and techniques for monitoring the range to or location of a person with respect to a monitoring station, such as the range to a child or patient. In general, systems heretofore proposed have been characterized by a high degree of cost and complexity. It is therefore a general object of the present invention to provide an apparatus of the described character that is of simple and economical construction, that may be worn by a child or other person without obstructing daily activity, in which the receiver employed by the parent or other monitoring person is transportable in the hand or pocket for monitoring the range to and activity around a child away from the home during a walk, for example, and that indicates an alarm condition in the event that the transmitter unit is removed from the child or other person to be monitored.